Sanding and polishing machine



July 27, 1937. A. MADsEN SANDING AND POLISHING MACHINE Filed May 16, 1936 2 SheetS--Sheel'I 1 July 27, 1937. A. MADsEN 2,088,330

SANDING AND POLIYSHING MACHINE Filed May 16, 1956 2 Sheets-Sheet 2 1 I Il Patented July 27, 1937 SANDING AND PoLIsHING MACHINE j Axel Madsen, Sioux City, Iowa, assignor to Albertson & Company, Inc., Sionx'City, Iowa,

a corporation of Iowa.

Application May k16, 1.936, Serial No. 80,031

10 Claims.

. The present invention relates to sanding and polishing machines, and is particularly concerned with improvements in the speed reducing gears and other details of the mechanism.

. .-5 In the sanding machines of the prior art, such as those shown in the prior patent of Frans O. Albertson, No. 1,954,977, issued April 17, 1934, .when equipped with a sanding disc of the type shown in the patent of Frans O. Albertson and Gustav A. Olsen No. 1,882,693, issued October 18, 1932, diiculties have been encountered in the maintenance of the speed reducing gearing and the armatures of the imotors, and many different types of gears have been tested and used. Among these were the worm and worm wheel arrangement shown in the prior patent of F. O. Albertson, mentioned above, and other arrangements.

The principal -diilculty is that the motor armatures would break down and become short circuited in some one or more of the many coils contained in the slots of the rotor, due to shock and vibration induced in 'the armature. by the gears and by the action of the sanding disc. 251.'.It -vwas apparently impossible to secure a long life :for the fmotor driven Sanders of that type with :the :geararrangements of Athe prior art, due to this vibration and shock.

.-One `of the objects of the present invention is 30 the Iprovision of an improved sanding'machine :which the motor armature is adapted to'. with- :stand'the ordinary conditions of'service to which 1. 40 :of .an improved gear structure including a cush- `:ioning device which is adapted to transmit power ggwithout loss and yet adapted to reduce the vi- I A.bration, shock and Wear which is caused by the 4i'transmission'of the power through speed Vreduc- 14245 :ing gearing.v

AnotherY characteristic of the prior art devices i .iwithout 'the use of the cushioning device dex ,fscribed was that there was an excessive wear on the .teeth of .the crown gear. `'l'."ne teeth not ,'50 only -wore on the driving side, but on the rear side, `and under such conditions the gears :in the f prior art devices were not capable of withstanding hard conditions of service for as long a periodas theyshould, and it was felt they should ,-7, 55 "stand up longer.

Another object is the provision of an improved speed reducing gearing `for sanding j and polishl 'zing machinesfwhich is more durableand more efu ricient, which eliminates geartooth vibration, and

1.560 whichmaybe manufactured atalower-vcostthan (Cl. '5l-170) the speed reducing gearing of the devices of the ,prior art.

Another object is the .provision of an improvedA cushioning device of the class described which is adapted to kwithstan'dfthe action of grease and other lubricants with which the gear housing is lled, sov `that the cushioningmaterial will not deteriorate due to the presence of the grease or other lubricant.

Other objects and advantages of the invention will be apparent from the following description -and the accompanying drawings, in which lsimilar 4characters .of `reference indicate similar parts v throughout the several views.

Referring to the drawings, Fig. 1 is a side elevational view of a sanding machine constructed according to the present invention, with the gear housingrbroken away, on a plane passing through the axis of the motor shaft, and the` gears and other mechanism Vin the gear housing shown Ain elevation; Y Fig. 2 is an elevational view ofY a sanding ma chine constructed according to the present 1n- Vention, with the-motor in'elevation and apart of the motor ,housing and the gear housing shown in section, o-n the plane of the line 2-2 of Fig. 1;

looking in the direction of the arrows, showing the detailsof construction of the cushioning de-v vice.

Referring to- Fig. l, ID indicatesv in its entirety the portable electric sanding machine, which comprises a handle II, electric switch I2, motor I 3, speed reducing gearing I4, and sanding disc I5.

The motor is Vdriven by electric current derived through electrical conductors which enter through the'protective rubber hose I6 into the handle II and switch box I 2. vThe switch is actuated by the switch lever Il, controlling the electric motor.

its armaturev I8 being mounted upon a motor shaft i9, which Yis rotatably mounted by means of suitable anti-friction bearings 2 located in the. H ,Y

socket 2i of the end plate 22.

The" speed reducing gearing I4 is contained in'V a housing 273, which comprises a cast metal member io-rmed with an o pen lower end 24 in Fig. 1

'and another opening 25 at one side for passing the spindle 26. y

v The housing 23 is secured to the lmotor end Aplate' 22 by a plurality of screw bolts 2l passing through the housing 23 and threaded into the` Gear housing 23 -is formed with f end plate 22. Y a bore 28 for receiving the bearing vbushing 2S for one end of the spindle 26. The housing wall ill Ysurrounding Ythe opening y25 is formed with a `counterbore k3l for receiving the outer race 32 of an anti-,friction bearing, which also comprises u theballs33fand inner `Vlrace k314.-V

The electric motor is of the usual constructlomf annular shoulder ll engaging the outer race 32.

l The sleeve 4G has a counterbore 42, which receives an oil seal comprising a sheet metal housing d3, a leather sealing member 44, and a garter spring [35. Two of the screws which hold the cover plate in place also hold a metal bracket l5 15, upon which is pivoted, by means of a screw bolt d?, a lever 48, having a pin 49.

The shaft 26 has a cylindrical body 53 and an annular shoulder 5i engaging the crown gear 52, which is located on the reduced cylindrical @O portion 53. The shaft has a smaller threaded portion 55s, which receives the nut 55 that clamps the crown gear against the annular shoulder 5i, and the end portion 5S of the shaft is of re duced cylindrical shape and is rotatably mounted in the bearing 29.

Shaft f3 also has an enlarged cylindrical portion 5l for receiving the inner race 34 and a still larger cylindrical portion 58 for engaging the leather sealing member 44 of the oil seal.

0 The cylindrical portion 59 of the shaft 26 supports a collar de, which has a pair of radially extending sockets or bores 6l, fitting the pin 49.

This collar is secured against rotation by a key "32, and when the lever 4% is pivoted until the pin SS is in a socket 6l the shaftl is secured against rotation. This is convenient when it is desired to attach or remove the sanding disc i5.

The left end of the shaft in Fig. 1 terminates lo in a threaded portion 63 for receiving the internally threaded hub Gd of the sanding wheel I5. Hub 613 has a sheet metal backing 65, which carries the rubber disc 55. Rubber disc 66 provides a support for a sanding disc 61, which is secured in place by a headed and externally threaded member threaded into the counterbore 55, as shown in my prior Patent 1,882,693, mentioned above.

The housing 23 has an inwardly projecting ledge or flange 69, which has a bearing sleeve 'lil pressed into a bore ll. The motor cover plate 22 has a bearing sleeve l2 pressed into a bore I3 and aligned with the bearing lil. A stub shaft Id is rotatably mounted in these bearings and carries a pinion I5, the teeth of which engage the crown gear 52. Pinion 'Hi has a tubular hub 'Vi with an outer cylindrical surface 78.

This cylindrical part is mounted in a-cylindrical bore 'I9 in a gear 553, which meshes with the drive shaft pinion 8l. The hub l1 has a plurality of slots 82, preferably equal in number, and equally spaced about its periphery.

The siots 82 carry a plurality of keys 83, which project from the slots into the arcuate slots 84 formed in the wall of the bore 19 of the gear 80. The arcuate slots 84 are much wider than the keys 83 and are adapted to provide space for a cushioning member 85, 86 on both sides of each key 83.

This cushioning member may be made of suitj impregnated with- The bore 36V` in the cover plate has a tightly pressed fit about, a sleeve (i5, which has an inwardly extending These arcuate slot 84. When placed in the slot, however, they conform to the shape of the slot, and therefore have curved cylindrical sides and radially projecting edges.

The ber blocks 85, 8S are preferably made of 5 some material which will withstand the action of grease or gear lubricant without deterioration, and they. are made larger than the space provided for them, in order that there may be no backlash. 10

In order to place the fiber blocks in their arcuate sockets, the hub 11 may be provided with apertures 87 for receiving the pins of a wrench. The gear 8G may be grasped by another suitable tool, and all of the blocks on the same side 15 of the keys 83 are first put in place.. Then, by the aid of the wrench fittings or tools, the gear 85 and hub H are so rotated that the keys 83 compress the blocks 85 tightly, and thus slightly enlarge the space into which the ber blocks '.20 85 are to bel inserted. The ber blocks 86 are then inserted and the pressure on the blocks released. The pinion 1S is then connected to the gear 8 through the resilient cushions 85, 86, which absorb the shock and vibration due toz25 the action of the teeth.

It will be noted that these cushions are interposed between the sanding Wheel l5 and the motor armature i8, so that the armature is vnot subjected to theshocks and vibration which'` 30 might result from the action of the grinding wheel, and it is found that when the present invention is employed no unusual troublefisl encountered with the motor armatures. As distinguished from the devices of theprior Vart,.the=..35 armatures withstand the use for which they are intended for long periods of time, and the insulation is not broken down; that is, ythe armature does not become short circuited.

It will thus be observed that'I have inventedgio an improved sanding machine having a cushioning means interposed between the sandingdisc and the motor armature. My cushioning.v device is adapted to withstand the action of grease or gear lubricant so that the gear housing 'may still. beig45 filled with the `usual lubricant,V and the fiber blocks are sufficiently rm so that there is no backlash due to the cushioning device.

The'blocks have sufficient resiliency, however, under the pressures to which they are subjected;.;,50 to constitute a resilient cushioning device, and they absorb the shocks and vibration due to the action of the sanding wheel and tothe teeth Vof the gears. When the sanding machine is equipped with this cushioning device, no excessivenr55 wear appears on the crown gear teeth, as has been'noted in the devices which did not employ such a cushioning device, and the cushioning device also serves to protect the armature from the vibration incident to the contact of the geants()- teeth.

While I have illustrated a preferred embodi-v ment of my invention, many modifications may be made without departing from the spirit of the invention, and I do not wish to be limited tof65 the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims. V f

Having thus described my invention, `what I claim as new and desire to secure by Letters Pat1-70 ent of the United States, is:

1. In a sanding machine, the combination of a motor, having an armature and a drive shaft, with a sanding device and a drive pinion for the sanding device, a spindle, speed changing gearsf75 between said spindle and said motor drive shaft, and a cushioning device interposed between certain of said gears to absorb the vibration and protect the armature from the effects of destructive vibration.

2. In a sanding machine, the combination of a motor, having an armature and a drive shaft, with a sanding device and a drive pinion for the sanding device, a spindle, speed changing gears between said spindle and said motor drive shaft, and a cushioning device interposed between certain of said gears to absorb the vibration and protect the armature from the eiects of destructive vibration, said cushioning device comprising a block of oil resistant fiber compressed between radially extending shoulders, one shoulder being carried by one gear, and the other shoulder being carried by another gear.

3. In a sanding machine, the combination of a motor, having a drive shaft, with a sanding device driven by said shaft, a gear housingfor speed reducing gearing, a spindle rotatably mounted in said gear housing, a crown gear on said spindle, and means for driving said crown gear from said motor drive shaft, including a resilient cushioning device whereby the vibration resulting from the teeth of the crown gear are not destructively transmitted to the armature on the motor drive shaft.

4. In a sanding machine, the combination of a motor, having a drive shaft, with a sanding device driven by said shaft, a gear housing for speed reducing gearing, a spindle rotatably mounted in said gear housing, a crown gear on said spindle,

and means for driving said crown gear from said motor drive shaft, including a resilient cushioning device whereby the vibration resulting from the teeth of the crown gear is not destructively transmitted to the armature on the motor drive shaft, said means comprising a gear driven from the drive shaft, a pinion for engaging the crown gear, said cushioning device interposing between said latter gear and pinion.

5. In a sanding machine, the combination of a motor, having a drive shaft, with a sanding device driven by said shaft, a gear housing for speed reducing gearing, a spindle rotatably mounted in said gear housing, a crown gear on said spindle, and means for driving said crown gear from said motor drive shaft, including a resilient cushioning device whereby the vibration resulting from the teeth of the crown gear are not destructively transmitted to the armature on the motor drive shaft, said means comprising a gear driven from the drive shaft, a pinion for engaging the crown gear, said cushioning device being interposed between said latter gear and pinion, said cushioning device comprising non-metallic, oil resistant blocks mounted on both sides of a n carried by said latter pinion.

6. In a sanding machine, the combination of a motor, having a drive shaft, with a sanding device driven by said shaft, a gear housing for speed reducing gearing, a spindle rotatably mounted in said gear housing, a crown gear on said spindle, and means for driving said crown gear from said motor drive shaft, including a resilient cushioning device whereby thevibration resulting from the teeth of the crown gear are not destructively transmitted to the armature on the motor drive shaft, said means comprising a gear driven from the drive shaft, a pinion for engaging the crown gear, said cushioning device being interposed between said latter gear and pinion, said cushioning device comprising non- Y ly projectinghub, av keycarried by said hub in a slot, a second toothed member rotatablyv mounted on said hub and having an enlarged internal slot providing a space on one side of said key, and an oil resistant fiber block in said space' adapted to cushion one toothed member from `the other toothed member in the drivingaction Yof said members.

8. In a sanding machine, the combination of a motor with a sanding member driven by said motor and shock resistant gearing interposed between said motor and said sanding member comprising the combination of awsupporting shaft with a toothed metal member mounted on said shaft, said toothed metal member having an axially projecting hub, a key carried by said hub in a slot, a second toothed member rotatably mounted on said hub and having an enlarged internal slot providing a space on one side of said key, an oil resistant fiber block in said space adapted to cushion one toothed member from the other toothed member in the driving actionrof 'said members, said internal slot having a space on the opposite side of said key also, and a second cushioning block arranged in said latter space under initial compression. y

9. In a sanding machine, the combination of a motor with a sanding member driven by saidS motor and shock resistant gearing interposed be-V tween said motor and said sandingv member comprising the combination of. a supporting shaft with a toothed metal member mounted on said shaft, said toothed metal member having an axially projecting hub, a key carried by said hub in a slot, a second toothed member rotatably mounted on said hub and having an enlarged internal slot providing a space on one side of said key, an oil resistant, ber block in said space adapted to cushion one toothed member from the other toothed member in the driving action of said members, said internal slot having a space on the opposite side of said key also, a second cushioning block arranged in said latter space under initial compression, and a plurality of other blocks and keys symmetrically arranged with'respect to said toothed members in theA same man-v ner.

10. In anabrading machine, the combinationr member being initially compressed whereby the variations in driving torque due to gears or to AXEL MADSEN. 

